An Improved Gain, Radiation Efficiency Enhanced, and Low-SAR Antenna for IoMT Long-Range Monitoring

A low Specific Absorption Rate (SAR) antenna with enhanced radiation efficiency and improved gain is proposed for further improvement of long-range biological monitoring systems within IoMT platforms. A unidirectional uniform current distribution form with high radiation efficiency and low SAR values was first theoretically calculated and proved, which is the current distribution with a ratio coefficient N. Subsequently, we achieved the desired current distribution by ingeniously utilizing the higher-order mode currents of the meandering dipole. The simulation current distribution in each section of this third-order mode dipole agrees with the theoretical calculations. The antenna operation frequency covers the ISM 2.45 GHz band (2.4-2.48 GHz), and the antenna has a peak SAR of 155.5 and 59.2 W/kg for 1-g and 10-g of tissue, respectively. The measured radiation efficiency is more than 2.4% in the band, the peak efficiency is more than 3%, the gain is more than -10.27 dBi in the band, and the peak gain is -8.53 dBi. In addition, based on the communication link budget analysis, it can be confirmed that the proposed antenna can establish a reliable communication link up to distances of 15 m (78 Mb/s) and 20 m (10 Mb/s) at 2.45 GHz, for transferring high data rate information.